This work examined four issues, in relation to both the experience of depression, and vulnerability to depression. There were four empirical studies, each with two parts. The first study examined the role of cognitions, such as overgeneralizations (Beck, 1963; Beck et al, 1979), and causal attributions (Abramson et al, 1978; Alloy et al, 1988). Their role as symptoms of depression, and as possible vulnerability factors, independent of current mood, was examined. In the first part of the study, clinically depressed patients, recovered subjects, and community control subjects were interviewed and given questionnaires. In the second part of the study a larger sample of students, some of whom became mildly depressed on beginning university filled in questionnaires at the start of term and again five weeks later. The same subject groups were the basis for the study on social factors, and the study on life events. The fourth study was also in two parts. A different sample of students were the subjects for the first part, and the same clinical and control groups participated in the second part. Factors found to be associated with the state of depression were: Internal, stable and global attributions for the causes of bad events, negative view of future outcomes, and negative view of self; social skill deficits and lack of social support; recent difficult life events. One factor failed to show any strong association with the depressed state – unrealistic goals. Factors associated with vulnerability to depression: Negative evaluations of future outcomes, and of self, unrealistic goals and, surprisingly, lower-than-normal goals; deficits in social skill (especially low self-confidence in social settings) and lack of social support; history-of difficult life events. Factors which failed to show association with vulnerability to depression: Causal-attributions for events; adverse reaction to depression itself. Deficits in social skill were associated with lack of social support. Depression proneness itself appeared to be a risk factor for negative life events.